1. Test & balance the water chemistry

In prevention and treatment, water chemistry is one of the most important steps to getting and keeping your pool algae-free.

You need to test your chlorine and pH levels with a good test kit (which are more accurate than test strips), and bring your pH level to about 7.8 by adding sodium carbonate to increase it or sodium bisulfate will also need to make sure the chlorine is at least above 1 ppm.

2. Turn on the pump

While treating your pool, your pump will need to be running 24 hours a day.

This keeps the water from stagnating and helping the algae to grow again.

The type of brush you use for this will depend on the type of pool surface you have.

If you have a concrete or plaster pool, you should use a wire or stiff pool brush. Scrub down all the surfaces of your swimming pool well, including steps, corners, pool wall, and under ladders.

5. Vacuum your pool

Vacuum your pool surface as thoroughly as you can to remove any algae or debris loosened while brushing, again making sure to clean under stairs, along the pool wall, and on steps.

While I love a good robotic pool cleaner, it's not the best for cleaning algae, so you're better off doing it manually.

6. Clean your filters

Your pool’s filter system will be an essential part of removing dead algae, so clean them out, rinse them off and make sure to backwash sand filters or D.E. filters. (You can clean your cartridge filter).

To backwash a filter, you will:

Turn the multiport valve handle to backwash or slide a push-pull valve.

Turn the pump back on.

Run until the water runs clear, usually 2-3 minutes.

Shut the pump off, move the valve back to filter, turn the filter back on.

Now it's time to shock your pool with a good calcium hypochlorite shock.

Yes, you're supposed to be shocking your pool weekly anyway, but getting rid of an algae overgrowth may require a little extra treatment, especially if it’s been neglected for a bit.

Pool shock is basically super-chlorinating your pool to kill off anything that shouldn’t be living there. How much you have to use will depend a lot on the type of algae you have.

Black algae usually requires shocking multiple times to get it clean and keep it from returning.

Make sure to wear gloves and clothes you don’t mind getting bleached in case you get it on you. If you choose powdered shock, first add the shock to a large bucket of water and stir it in.

Follow the manufacturer’s directions for how much to use for your swimming pool, then pour the shock mixture all around. Liquid shock can be poured directly into your pool without mixing it with water.

It’s best to shock while the sun isn’t out so that your pool’s chemistry is not affected by environmental factors.

The water might look cloudy after this treatment, but your pool’s filter should clear it up in a day or two.

5. Vacuum your pool

It’s best to vacuum your pool’s surfaces after brushing to remove loose particles removed during that process.

6. Use a good algaecide

Since algaecides are made specifically for keeping algae at bay, regular use of it in your pool will keep it clean and clear.

There are specific algaecides available for the various types of algae for times when there is already a growth and you know what type of infestation you are facing.

But multi-purpose algaecides will help prevent them before they are a problem.

What is algae?

According to study.com, “algae is the name given to a large and diverse group of oxygenic, phototrophic, eukaryotic microorganisms. Algae are eukaryotic, which means they have a nucleus.”

Or more simply put, a slimy plant-like organism that produces oxygen through photosynthesis (totally paraphrased).

Algae comes in different forms like seaweed and pond scum. In other words, like other plants, it's important to our existence, but there’s no reason you need to harbor it like fugitives in your swimming pool.

If you don’t house it, some other pond, pool or unsuspecting body of water will!

You might wonder why algae in the pool matters until you’ve been infested with it.

But there are really only a few specific types in these families that you need to worry about as a pool-owner:

Green algae

Green algae is the most common type of algae with around 7,000 species in its family. Some of them are found only in salt water, but others are found floating around in pools, ponds and rivers.

Green algae is the easiest to get rid of, and can usually be treated successfully with a little extra chlorine or algaecide.

Mustard algae

Mustard algae (or yellow algae) has beta carotene, which gives them a more yellow-like appearance.

It’s a more difficult algae to get rid of than green algae because of its chlorine resistance, and is also a little harder to detect because it can often be mistaken for sand or pollen because of its light appearance.

Getting rid of mustard algae usually requires a few extra steps like shocking and brushing.

Black algae

Black algae is also called blue-green algae, but it’s actually not algae at all. It’s a bacteria called cyanobacteria and grows in large masses.

This one is the most frustrating to get rid of because it takes root in cracks and crevices, making it difficult to remove. It also has a protective layer, often called a head that makes it particularly resistant to chemicals.

To get rid of black algae is a lengthy process, sometimes even involving draining the pool and acid washing the pool surface.

Pink algae

Pink algae is another form of bacteria and it appears in cracks and corners and spreads quickly.

It is also chlorine resistant, but can be treated with large amounts.

Getting rid of pink algae is not quite as intensive as getting rid of the black kind, but it will usually require shocking and brushing, sometimes repeatedly.

Why is algae bad for my pool?

So, why is it bad for your pool?

Well, besides being an eyesore, it can wreak all kinds of havoc on your summer fun in a few specific ways:

1. Erosion & staining

Keeping your pool water balanced is important for many reasons, but for your pool surfaces, it’s essential.

These things will erode both concrete and fiberglass surfaces over time, and coupled with elements like dirt, skin particles and algae can cause discoloration and staining.

2. Clogged filters

Algae has a tendency to clump together and reproduce, making it extremely difficult for your pool filter to do its job.

The black kind in particular has a sticky surface and takes root in crevices and openings. It clings to the mesh and openings in filters, hanging on to other spores and debris until it forms clogs impossible to filter out normally.

3. Germs

While algae itself is not harmful to humans or pets, it can trap bacteria within it like E. coli, circulating the harmful germs in the pool water.

4. Slippery steps

Algae is slimy and slippery, so when it starts to grow on ladders, on the pool wall, and steps, it can make for some slick areas around the pool.

Why & how does algae grow in my pool?

Algae spores are constantly making their way into your pool either through environmental elements like wind and rain, through swimsuits, or objects that were recently in the ocean and through people dragging them in.

Once the spores reach the water, ideal environments then cause them to bloom and reproduce.